1. Technical Field
This invention relates to imaging systems, and more particularly, to systems that may image visible or infrared wavelengths.
2. Related Art
Infrared imaging systems provide image detail that may not be identifiable in a visible image. Some infrared imaging systems amplify the light in the visible or visible and short wave infrared spectral regions (wavelengths less than 1.2 μm). The amplified light is generally reflected light produced at night by outdoor lighting, the moon or by starlight. In these systems, the imagers' detection capabilities are dependent on the ambient lighting conditions. Thus, these systems are unusable in foggy or heavily overcast evening situations, or in unlighted enclosed spaces, such as caves or smoke filled buildings.
Other systems may operate in the mid wavelength infrared spectral region (wavelengths between 2.8 μm and 5.5 μm) or the long wavelength infrared spectral region (wavelengths between 7.5 μm and 14 μm). These systems may detect thermal radiation emitted by warm objects, whether animate or inanimate, irrespective of the lighting conditions. These ambient light and thermal imaging systems utilize separate cameras to create a superimposed image of the scene having both visible and infrared components. One camera captures the visible imagery while a second camera captures the infrared imagery. The images are then post-processed to obtain a composite image that is presented to a display or observer. Thus, these imaging devices require multiple camera systems and complex electronics in order to create a combined visible image.